Internal-combustion engine fuel and speed control



L. LEE 1|'- June 30, 1953 INTERNAL-COMBUSTIN ENGINE FUEL AND SPEEDCONTROL 3 Sheets-Sheet 1 Filed April 8. 1949 klo Su l WIEN www/ f NRMEATTORNEY l.. LEE 1L 2,643,513

INTERNAL-COMBUSTION ENGINE FUEL AND SPEED CONTROL June 30, 1953 FiledApril s, 1949 3 Sheets-Sheet 2 Awww.

INVENTOR Zegyio/z eel BY ATTORNEY INTERNAL-COMBUSTION ENGINE FUEL-ANDSPEED CONTROL Filed April 8, 1949 l.. LEE Ir June 30, 1953 3Sheets-Sheet 5 lNvENroR Zeggia/zeel BY ATTORNEY Patented June 30, 1953INTERNAL-COMBUSTION ENGINE FUEL AND SPEED CONTROL Leighton Lee Il, RockyHill, Conn., assigner to Niles-Bement-Pond Company, West Hartford,Conn., a corporation of New Jersey Application April 8, 1949, Serial No.86,356

310 Claims. (Cl. (iO-39.28)

This invention pertains to automatic control apparatus for internalcombustion engines and more particularly has reference to controls forinternal combustion engines of the gas turbine and jet types.

The invention is especially applicable to internal combustion enginesfor propeller-propulsion, jet-propulsion (turbo-jet) or propeller-andjet(prop-jet) propulsion of aircraft. Such engines usually include an airinlet, an air compressor, one or more combustion chambers, a gasturbine, and a tail pipe for discharging combustion gases to theatmosphere, except that ram-jet engines have no air compressor or gasturbine. Associated with these engines is a fuel system including a pumpfor delivering fuel to the combustion chambers. This invention concernsapparatus to control the engine speed and power by controlling the fuelsupply as a function of several variables, including engine speed,engine temperature, and other engine operating conditions, and a manualcontrol.

Owing to structural and metallurgical limitations, engines of the typereferred to cannot be safely operated at speeds and temperaturesexceeding predetermined limiting values, but for maximum economy ofoperation, both speed and temperature of engine must be maintained at ornear these limiting Values. On the other hand, While engine speed is acritical factor in flight performance of aircraft, an engine cannot beoperated at maximum speed in all flight maneuvers, at all flight speeds,or under all flight conditions. Fuel control apparatus should,therefore, enable the operator to vary engine speed as desired from aminimum required power to the predetermined limit of speed and fullpower. The control of engine temperature is preferably an automaticfunction of the fuel control apparatus, during transient conditions.

The value of engine speed corresponding to any given value of fuelfiovv, varies as a function of the altitude of night, night speed, airdensity at the engine air inlet, engine torque, fuel quality and a Widevariety of other factors. For precise regulation of engine speed or toavoid excessive temperatures, it is therefore not feasible to relysolely upon automatic regulation of fuel ow as a function of variableswhich exclude engine speed and temperature.

Heretofore it has been proposed to control engine performance byregulating the fuel supply to the engine by means of a regulator, in theform of a self-contained unit running on its own fluid, which producesan hydraulic pressure that transmitted to a variable delivery fuel pumpso designed that its delivery varies in a desired relationship to thetransmitted pressure. Such a control apparatus Was disclosed in myapplication for Control Apparatus for Turbojet Engines, Serial No.746,975, filed May 9, 1947, and assigned to the same assignee as thisapplication. Recent experience in operating aircraft under conditions ofvery low temperatures has shown that better control performance may beobtained if the fuel control Works directly on the fuel supplied to theengine rather than on the fuel pump. Accordingly, the new type of fuelcontrol herein disclosed is devised to function either by regulating avariable delivery fuel pump or by directly regulating the fuel supply tothe engine and is, not only capable of performing the functions of theapparatus disclosed in my prior application, cited, but also has someadvantages not offered by that apparatus.

The objects of this invention are:

(l) To provide an improved fuel control system wherein the fuel flowregulating unit acts either upona variable displacement fuel pump ordirectly on the fuel supplied by a constant displacement pump toregulate its flow to the engine.

(2) To provide for an internal combustion engine, an improved fuelcontrol apparatus which will produce a constant engine speedcorresponding to the control lever position selected by the operator.

(3) To provide such a control apparatus Wherein the maximum safe speedand temperature of the engine will never be exceeded.

(4) To provide such a control which will so function that the engine canbe accelerated and decelerated at a maximum rate, correspondingrespectively to the maximum temperature permissible ahead of theturbine, and to -the minimum fuel now corresponding to burner blowoutconditions, In addition, the fuel now is never great enough to causestalling of the compressor.

(5) To provide improved fuel and speed control apparatus for an internalcombustion engine employing a plurality of component coordinatedhydraulic systems for regulating fuel delivery, said systems beingresponsive to manual control and to pressure, speed and temperatureconditions of the engine.

(6) To provide improved pressure regulating :and pressure responsivecontrol elements which may be used in hydraulic apparatus such asmentioned above.

(7) To provide in such apparatus, means for iclosely controllingacceleration and deceleration ofthe engine, as a function of a pressureresponsive system, and improved means for anticipating speed changes sothat hunting is eliminated or reduced to a minimum.

With these and other objects in view which may be incident to myimprovements, my invention consists in the combination and arrangementof elements hereinafter described and illustrated in the accompanyingdrawings, in which:

Figure l shows, somewhat diagrammatically, an engine suitable forpropeller-and-jet propulsion of aircraft, together with its associatedfuel ow regulator operating in conjunction with a constant displacementpump and manual control lever, and the principal connectionstherebetween;

Figure 2 shows an alternate arrangementof the apparatus of Figure 1,wherein the fuel flow regulator controls a variable displacement fuelDump;

Figure 3 shows, also somewhat diagrammatically, a control apparatusembodying the principles of my invention;

Figure 4 is a central vertical section of part of the regulating unitshowing the servo valve, speed governor and manual control cam shaftassembly; and

Figures 5 and 6 are fragmentary vertical sections along the lines 5 5and 6-6 of Figure 4.

Referring to Figure l of the drawings, there are shown, as the principalelements of the engine above referred to: a supporting casing I, an airinlet 2, a multistage air compressor 3, a compressor rotor shaft 4; oneeach of a number of combustion chambers 5; one each of a series ofcombustion nozzles E, connected respectively to two generally circularfuel manifolds 8 and 9, by means of conduits I and II; a` multistage gasturbine I2, a turbine rotor shaft I3, connected to the compressor rotorshaft 4; a tail pipe I4 for discharging exhaust gases from gas turbineI2; a center bearing I and end bearings IS and I1, supported by casing apropeller shaft I8, carrying a propeller I9, and a gear train 2,0,connecting shafts 4 and I8 for rotating propeller |9 at a speedproportional to engine speed and for operating the fuel pump and otheraccessories. The construction of a turbo-jet engine used solely for jetpropulsion is similar to that of the engine shown in Figure 1, exceptfor the omission of the propeller shaft I8 and corresponding modicationof the gear train 20.

A constant displacement fuel pump 2| draws fuel from a supply tank 22through a conduit 23 and delivers it through a conduit 24 to the fuelflow regulating apparatus diagrammatically indicated at 25 and shown'indetail inFigure 3. From fuel regulator 25 the fuel flow through aconduit 26 to a pressure-responsive flow-divider 21, and from thencethrough conduits 28 and 29 to fuel manifolds 8 and 9; respectively, inthe engine Pump 2| is operated by a drive shaft 30 connected to geartrain 20 in the engine, or any other suitable source of power. The fuelregulator 25 acts to vary the quantity of fuel delivered to the engineper unit of time, as required by the operating conditions, and thedifference between the fuel delivered by the pump 2| and the quantityrequired by the engine is by-passed through a conduit 3| to the inletside ofthe pump through a relief valve in the fuel regulator 25.

n each of the combustion nozzles 6 there is a series of fixed slots, oneof which is indicated at 1, through which fuel enters the nozzles 6 fromconduit I0. The fuel iiow fromr the nozzles is '4 directly proportionalto the effective area of slots 1 and is a square root function of thedrop across the nozzles between the pressure in conduit I0, which issubstantially equal to the pressure in conduit 2B, and the pressure (p2)in the combustion chamber 5. As it is desired to limit the range of fuelpressure so that its value at maximum fuel flow is less than thatcorresponding to the square root function of the drop across slots 1,the nozzles 6 are provided with auxiliary slots 32 supplied by manifoldI I connected to the pressure-responsive flow-divider 21 which opens ata predetermined value of the pressure (pm) in conduit 26. In thismanner, the pressure (pm) may be maintained suflicientlyhigh to producesatisfactory nozzle discharge without requiring the fuel regulator 25and pump 2| to operate under nfavorable pressure conditions at maximumThe fuel flow regulator 25, shown diagrammatically in Figure 1, and indetail in Figure 3, is connected by a conduit 33 to a source ofcompressor inlet pressure (pi) in the engine, and by a conduit 34 to acorresponding source of compressor discharge pressure (p2). Assubsequently explained, the fuel regulator 25 is responsive to thepressure differential (pz-1p1) which is a function of air flow throughthe engine. The value (p2-p1) increases as the engine speed increasesand as the altitude of flight, or temperature of entering air decreases,and is also a function of the compressor characteristics.

A main drive shaft 35 in the fuel regular 25 is driven by the engine ata speed proportional to engine speed and a manual control shaft 36 isrotatable in response to movement of a shaft 31 to which is xed theengine control lever 38. Control lever 38 is manually operable inreference to a scale 39 on a fixed quadrant 40, the scale 39 beingcalibrated in terms of engine speed (R. P. M.)

Figure 2 shows an alternate arrangement of the fuel flow regulatingapparatus of Figure l, wherein the fuel flow regulator 25 operates inconjunction with a variable delivery fuel pump 4| which draws fuel froma supply tank 22 through a conduit 23 and delivers fuel through conduit24 to regulating apparatus 25, The output of pump 4| is varied by therotation of a shaft 42 by means of an arm 43 which is pivotallyconnected to a piston 44 that reciprocates in a cylinder 45. A conduit46 connects one end of cylinder 45 to the discharge conduit 24 of pump4I, while the other end of cylinder 45 is connectr ed by a conduit 41 toconduit 26 leading from regulating apparatus 25 to nozzles 6 incombustion chamber 5 of the engine I. A spring 48 is interposed betweenpiston 44 and the left end of cylinder 45 so that piston 44 moves inresponse to the pressure in conduit 24opposed by the pressure in conduit26 and spring 48. When variable delivery fuel pump 4| is used, itreplaces constant delivery fuel pump 2| of Figure 1, with some minorchanges in the connections between the pump and certain elements ofcontrol apparatus 25, as hereinafter described.

Referring to Figure 3, there is shown, somewhat diagrammatically, anembodiment of my invention as indicated in Figure l, all the principalelements of which are enclosed in a casing 5| having an externalconnection with conduit 33 for supplying air to the apparatus at thecompressor inlet pressure (p1), and with conduit 34, for supplying airto the apparatus at the compressor discharge pressure (p2).

The control apparatus shown in Figure 3 is a self-contained hydraulicsystem employing the interior of casing 5| as a reservoir 52 which ismaintained approximately full of liquid fuel at the inlet pressure (pi)of fuel pump- 2| in order to permit the working elements to operate in alubricating bath. This control apparatus comprises five mechanicallyand/ or hydraulically operated cooperating units as follows:

(l) A by-pass relief valve for regulating the pressure (pf) of theliquid fuel in the conduit 24 on the downstream -side of fuel pump 2|.

(2) A main fuel metering valve which varies the flow of fuel to theflow-divider 21 and burner nozzles 0, as a function of the pressure rise(p2-p1) across the compressor 3, to meet the specified conditions ofconstant engine speed for any given setting of the manual control and ofacceleration and deceleration of the engine; the metering valve portsbeing contoured to give the necessary relation between fuel ow andcompressor sensing pressure (p2-p1).

(3) A manual control whereby the operator may vary the engine speed asdesired throughout its permissible operating range, including a cutolfvalve for completely stopping all fuel flow to the engine.

(4) A speed control comprising a servo valve, responsive to a speedgovernor driven by the engine, which varies the pressure equilibrium onthe relief valve (l) above and thereby varies the pressure and therewiththe rate of fuel delivered to the engine through the metering valve (2)above. This variation in rate of fuel delivery will result in correctionof the engine speed in any desired direction. The speed control systemincludes an inertia mechanism for immediately anticipating the action ofthe speed governor, in accordance with a change in manual controlsetting, whereby the hunting effect of the speed control is eliminatedor reduced to a minimum, and the engine made more quickly responsive tothe manualcontrol.

(5) A thermal control for overriding the manual control as a function ofengine temperature. Normally, there is no liquid flow through thethermal control, but when the maximum allowable temperature is exceeded,liquid flows through the thermal control and lowers the governor servopressure (ps) on the by-pass relief valve which reduces the fuel pumpdischarge pressure (pf). This reduction of fuel pump discharge pressurereduces the rate of fuel supply to the engine and results in reducedengine speed and temperature.

Referring particularly to Figure 3, liquid fuel is supplied from fuelsupply tank 22 through ccnduit 23 to fuel pump 2 l, at a pump inletpressure (p1), either under a gravity head as shown in Figure 3, or froma booster pump (not shown) between tank 22 and main fuel pump 2|. Fuelissuing from pump 2| flows through conduit 24 and branch conduit 53 to aby-pass relief valve 5ft which comprises chambers 55 and 55 betweenwhich is located a valve seat 51. Cooperating with valve seat 51 is avalve 58 having an integral valve stem 59 slidably mounted in a sleeve50 fixed to the wall of chamber 55 by a tap bolt El. Valve 58 isthreadedly attached to a piston 62 slidably mounted in a sleeve 03 whichis secured by an outer sleeve 64 xedly mounted in a cylindrical recess65 in the right end of chamber 55. A plug $5 closes the right end ofchamber 5S and forms with the right end of piston 52 a cylindrical space61 in which is mounted a spring 6 68 biasing valve 58 toward its seat`51. A conduit 69 leads from space 31 to a conduit 19 which connectswith the manual and thermal controls hereinafter described. Chamber 53is connected by conduit 3| with conduit 23 on the inlet side of pump 2|.

From the foregoing description, it is clear that valve 59 is subject tothe pump delivery pressure (pf) in conduits 24 and 53 and chamber 55.When this pressure (pf) exceeds the pressure in space 61, plus the forceof spring 68, valve 58 will open and permit liquid fuel to flow fromchamber 55 through chamber 56 and conduit 3| to the inlet side of pump2|. The fuel thus bypassed around the pump will reduce the pressure (pf)in conduit 24 until it balances the pressure in space 6l plus the forceof spring B8. As valve 58 will. float most of the time just off of itsseat 51, guide stem 59 closely fitting in sleeve 60 is provided tosteady the motion of valve 58 and prevent minor fluctuations andchattering.

Conduit 25 delivers fuel at pump outlet pressure (pf) to chamber 1| inwhich is mounted a sleeve 12, the upper end of which forms a seat 13 fora manually operated cut-olf valve 14. Mounted on stem 15 of valve 15 aretwo annular flanges 1E and 11 which reciprocate in cylinders 18 and 19and serve as guides for the movement of valve 15 and hydraulicallybalance the valve. Flanges 15 and 11 are provided with gaskets whichform fluid-tight joints between the flanges and their cylinders 18 and19, respectively. The upper end of cylinder 18 and the lower end ofcylinder 'i9 open into a chamber 80 in the upper part of casing 5|, andcylinder 19 is vented to cylinder 18 through a passageway 8| in stem 15of valve l5.. A horizontal passage 82 connects chamber 30 with anotherchamber 33 which is hermetically sealed by a cover plate 84 and gasket95 held in place by tap bolts 86. Manual control shaft 35 is journalledin the rightside wall of chamber B3 and extends into said chamberwherein are located cams 81 and 88, each of which is adjustably mountedon shaft 33 by an integral split collar and bolt (see Figs. 5 and 6).

The inner end of shaft 35 Vcarries a crank arm 83 which is adjustablysecured to the shaft by a set screw 99, and carries at its other end apin 9| which extends to the left, at right angles with crank arm 89, andengages valve stem 15 between fixed collars 92 on said stem. The centerline of shaft 3S is off-set from the center line of valve stem 'l5 bythe throw of crank arm 89 which is equal to the total vertical travel ofvalve stem in cylinders 19 and 19. Shaft 35 is rotated by the throw ofmanual control lever 39, between its 0 position on scale 39,corresponding to minimum engine speed, to its 90 position, correspondingto maximum engine speed, and this 90 rotation of shaft 35 varies theposition of valve 14 from its lowest operating position just off of itsseat 6| to its highest or full open position. Rotation of manual controllever approximately 5 below its minimum speed (0) position causes shaft36, arm 89, and pin 9| to seat valve 11| firmly on its seat 13 whichcompletely cuts off the flow of fuel to the engine, as is hereinafterdescribed.

When valve 14 is in open position (as in Fig. 3), fuel ows through valvechamber 93 `and passage 94 to cylinder 95 of main fuel metering valve 93which reciprocates ina valve sleeve 91 fiXedly mounted in cylinder 95.Between cylinder 95 and sleeve 91 are two annular spaces 98 'and 99.which are separated from each other by a flange |00 which extendsoutwardly from sleeve 91 and contacts cylinder 95 with a fluid-tight t.Upper and lower flanges and |02 similarly t cylinder 95 :and preventescape of liquid therebetween. A plurality of ports |03 in the upperpart of sleeve 01 admit liquid fuel from space 98 into the in- .reriorof sleeve 91 and a plurality of ports |04 in tlfe lower part of sleeve91 permits fuel to iiow from the interior of sleeve 91 into space 99when valveaSS is open, and from thence through conduit26 -toflow-divider 21. Ports |04 have contoured shape, elongated in a verticaldirection, and constitute the variable metering orifice of meteringvalve 96.

Extending upwardly from valve 96 is a reduced fortiori which is integralwith a cylindrical cuide member |06 that closely fits in sleeve 91 andserves `to guide and steady the moveemnt of -ralve 96 in said sleeve.

The valve member 96-I05-I08 has a central, .'longitudinal bore throughwhich passes a rod .|01 having near its lower end Aanoutwardly-extending, integral flange |08 which contacts the lower end ofvalve 96 and forms a seat therefor. A pair of lock nuts |09 are threadedon the upper end of rod |01 and serve to hold valve member d5-|05-i06firmly against flange |03 and thus in fixed relation to rod |01.

Threaded on rod |01 above nuts |09 is another lock nut H0 which servesas an adjustable seat for a sleeve which is threaded over the upper endof rod |01. The lower end of sleeve is provided with anoutwardly-extending flange 2 `which serves as a base for apressure-responsive -bellows ||3` whose upper end is attached to a.hollow cylindrical plug ||4 which is seated in a bore ||5 in the tcp ofcasing 5|. Plug ||4 has a depending tubular extension 6 which terminatesin an inwardly-projecting flange that serves as a seat for a spring |1whose upper end bears against a pair of locked nuts H8 threaded on theupper end of sleeve and which serve to adjust the compression in spring||1. Seated in a recess in the top of sleeve is alight spring ||`9 whosecompression is adjusted by a tap bolt |20 threaded through a cover plate|2| which hermetically seals the upper end of bore I5 and forms the topof a chamber |22 which is connected by conduit 34 to the compressordischarge chamber in engine `and receives air under compressor dischargepressure (p2).

Cylinder 95 and sleeve 91 open into a chamber |23 which is connected bya conduit |24 to chamber 52 and by a conduit |25 to conduit 3|. Aconduit |26 connects conduit |25 with chamber 52. From this arrangement,it will be noted that chamber |23 is supplied with liquid fuel. underpump inlet pressure (pi) through conduits 3| and |25, and chamber 52 isalso supplied with liquid fuel under the same pressure (pl) throughconduits 3| and |26. A passage |21 and passage 82 connect chamber |23with chamber 83 so that the chamber 83 is also supplied with liquid fuelunder a pressure 0pt).

Seated in the bottom of cylinder 95 is a flanged disc |28 which servesas a base closure of a pressure-responsive bellows |29 whoserupper endis closed :by `a cover |30 -threadedly connected to the lower end of rod|01 and secured in adjusted relation to said rod by la lock nut I3 Atubular shim |32 forms the outer wall of a chamber |33 and serves as aseat for valve sleeve 91. Chamber |33 is connected by a drain pipe |34to conduit 3| so that any liquid fuel that leaks past valve 196 intochamber |33 is returned to conduit 23 on the inlet side of pump 2|. Disc|28 is provided `with an aperture |35 through which the interior ofbellows |29 receives air through conduit 33 from air inlet 2 under apressure (p1).

Referring now to Figures 3. 4 and 5, it will be noted that theright-hand part of casing 5| is provided with two vertically disposed,cylindrical bores |36 and |31, each in axial alignment with the verticalcenter lines of cams 88 land 01, respectively. Slidably and rotatablymounted in Ithe `upper end of bore |36 is la plunger |38 whose upper endis internally threaded for the reception of the threaded stem of a camfollower |39 .which is mounted on top of plunger |38 and contacts theface of cam 08. Follower |39 has a lateral extension to the right withan aperture for engaging a pin which is xed in the wall of bore `|36 andextends upwardly into chamber 83. (see Fig. 4). Plunger |38 is providedaround the periphery of its upper end with a series of gear teeth |40(Fig. 5) which are pitched at an angle of approximately '1 with thevertical axis of plunger |38. Gear teeth |40 mesh with a worm |4| on theinner end of a shaft |42 rotatably mounted in bore |43 in casing 5|.Bore |43 is pitched at an angle of approximately 83 with the verticalaxis of plunger |38, so that worm |4| will properly mesh with teeth |40in plunger |38. The outer end of shaft |42 is somewhat enlarged andprovided with threads |44 which engage internal threads in casing 5|.The outer end of shaft |42 has a transverse slot |45 for the receptionof a screw driver `by which shaft |42 can be rotated. A lock nutthreaded on threads |44 provides a means for locking shaft |42 in fixedposition. When shaft |42 is rotated. it turns plunger |38 about itsvertical axis, and since the stem of cam follower |39 is prevented fromrotating by its engaging pin, the turning of plunger |38 labout itsvertical axis causes it to move up or down with reference to camfollower |39 yand thus adjusts the position of plunger |38 relative tocam follower |39.

Returning to Figure 3, it will be noted that the lower half of plunger|38 is counterbored to receive a spring |46 which seats at its lower endupon an annular thrust bearing |41 (preferably of carbon). Bearing |41is supported by a conical washer 48 which rests upon the conicalshoulder of a triple-spool servo valve |49. The lower end of servo valve|49 terminates in an annular disc portion |50 which is provided atdiametrically opposite points in its bottom face with two notches, cachof which receives the lowel` end of an L- shaped arm |5| pivoted to lugs|52 on the base |53 of a ily-weight speed governor. The lower end ofbase |53 is provided with a splined aperture |54 for the reception ofthe splined neck |55 of governor drive shaft 35 driven by the engine(see Fig. 4). Base |53 is supported by a ball `bearing |56 mounted inthe bottom of casing 5| and is surrounded by a packing gland |51 toprevent escape of liquid fuel which may leak out from chamber 52 betweenthe wall of casing 5| and bearing sleeve |58 of base |53.

Sleeve |58 is provided with a channel |59 which conducts liquid fuelfrom chamber 52 to a running seal |60 at the bottom of sleeve |58. Anyliquid fuel that works past seal |60 is returned to the fuel supply tank22 by a drain conduit |6|. The upper end of base |53 is counterbored toreceive a pressure responsive bellows |62 whose upper end is sealed by adisc |53 having an upwardly extending stem which slidably projects mto asocket in the lower end of servo valve |49.

'The interior of bellows |62 communicates through a central passageway|64 and radial passageway |65 with a circumferential groove |66 in theouter face of base |53. Groove |66 is connected by passageways |61 and|68 with a bore |69 in casing in which is xedly mounted a bearing sleeve|16 which serves as a journal for a rotating spindle |1| mountedtherein. Spindle |1| is provided with a transverse passageway |12 thatconnects with passageway |58 through registering ports |13 in sleeve|10, and a central passageway |14 which communicates with la space |15over the upper end of spindle I1 Fixedly attached to spindle |1| andmounted for rotation on the upper end of sleeve |10 is an annular discmember |16 which has at its lower outer periphery a gear |11 and on itsupper face two lugs |18 and |19 for the attachment of a spiral spring|88 by means of a set screw |81 which is threaded through lug |19 andpinches the outer end of spring |88 against lug |18 so as to anchor itthereto. Mounted for rotary movement about the upper end of spindle |1|is a cylindrical inertia member |82 having a radial passageway |83 whichcommunicates with a groove |84 in the outer face of spindle I1 A secondU-shaped passageway |85 in inertia member |82 leads from space |15 atits upper end to the face of spindle |1| at its lower end. Spring |88 isattached at its inner end to a downwardly extending tubular boss oninertia member |62 so that the rotation of spindle |1| is transmitted toinertia member |02 through said spring. So long as spindle |1| andinertia member |82 are rotated at the same speed (R. P. MJ, the lowerend of passageway |85 is partially closed by the outer face of spindle|1|, but if spindle |1| is accelerated, say in a clockwise directionwhen viewed from above, the mass of inertia member |82 causes it to lagbehind spindle |1| so that groove |84 is progressively brought intodecreasing register with the lower end of passageway |85 by virtue ofthe inclination of the lower edge of said groove, thereby furtherclosing communication between passageways |85 and |83. At the same time,the lag of inertia member |82 winds up spring |80, thereby increasingits tension and imparting an increased rotating force to inertia member|82 which increases its speed (R. P. M whereupon spring |80 graduallyunwinds and returns to its original tension, so that when spindle |1|and inertia member |82 are again rotating at the same speed, the end ofpassageway |85 is again partially closed by the outer face of spindle|1| to the same extent as before acceleration of spindle |1|.Conversely, when spindle |1| is decelerated with respect to the speed ofinertia member |82, the reverse of the foregoing action takes place, sothat the degree of opening of passageway |85 corresponds at all times tothe relative speeds of spindle |1| and inertia member |82. A hollow cap|86 is threadedly mounted on disc |16 and affords a cover for inertiamember |82. The upper end of cap |86 is threaded for the reception of anadjustable plug |81 which varies the tension of a spring |88 interposedbetween plug |81 and the Lipper end of inertia member |82 so as tomaintain a predetermined downward force on member |82 lin opposition tothe upward force of the liquid pressure in space |15. Cap |86 is alsoprovided with a plurality of ports |89 which permit liquid fuel toescape from the interior of said cap into chamber 52 from which saidliquid fuel is returned to the inlet side of fuel pump 2| by conduits|90, |26, |25 and 3|.

Liquid fuel under pressure (Pf) is supplied from chamber 93 to spindle|1| through a conduit |92, bore |93, restriction |94, and passageways|85, |13 and |12. A threaded plug |96 permits the removal of restriction|98 for replacement by a restriction of another size, so that the iiowof liquid fuel into spindle |1| may be adjusted as desired. The liquidfuel which is supplied to spindle |1| also enters bellows |62 throughcommunicating passageways |68, |61, |65 and |58, hence the liquidpressure in bellows |82 is varied by the relative rates at which liquidfuel enters spindle |1| through restriction |98 and escapes throughpassageways and |83 which former is controlled by groove |84 mentionedabove. Spindle |1| -is driven by the engine at a xed speed ratiotherewith and with speed governor arms |5 by drive shaft 35 throughintermeshing gears |11 and |91. As long as spindle |1| and inertiamember |82 are rotating at the same speed (R. P. M.) the lower end ofpassageway |85 has a definite position in relation to the lower, in-

clined edge of groove |84, as determined by the vertical position ofmember |82 with reference to spindle |1|, which in turn depends upon thebalancing of the downward force of spring |88 on member |82 and theupward thrust of the liquid fuel in space |15 on said member.

At a steady engine speed, spindle |1| and inertia member |82 will berotated at the same speed and the position of the lower end ofpassageway |85 with reference to the lower, inclined edgeof groove |84will be such that liquid fuel will escape from spindle 1| throughpassageway |85 as fast as it enters through restriction |98, regardlessof variations in pressure of said liquid fuel in conduit |92, since anyimpedance of this flow through passageway |85 will immediately result ina corresponding increase in pressure in space |15 which will lift member|82 against spring |88 and increase the opening from passageway |85 togroove |84 until steady flow ensues.

If now the engine accelerates its speed, the speed of spindle |1| willtemporarily increase beyond the speed of member |62, due to the inertiaof the latter, and relative rotation of member |82 on spindle |1| willdecrease the opening of passageway |85 with resulting increase in liquidpressure in space |15. This will lift member |82, increasing thecompression of spring |88, and correspondingly increase the pressure inpassageways |14, |12, |68, |61, |65, |88 and bellows |62 ,until thespeed of member |82 again equals the increased speed of spindle |1|,whereupon the increased opening of passageway |85 will again equal thatof restriction |94 land the pressure in bellows |62 will return to itsoriginal value. Conversely, a deceleration of the engine will result inthe reverse of the above actions, and therefore the pressure in bellows|62 is correspondingly responsive to the acceleration or deceleration ofengine speed.

Speed governor arms |5| are enclosed in a hcllow cylindrical housing |98fixed to base |58, and the upper ends of said arms are weighted so that,as they are rotated by shaft `35 and base |58, they move outwardly bycentrifugal force in proportion to the speed of rotation, and therebyraise servo valve |89 to which they are connected. Servo valve |48 isslidably and rotatably mounted in a valve sleeve |99 which is fixedlypositioned in bore |38 and is provided with three circumferentialgrooves 208 on its outer surface which communicate through ports withconduits leading into bore |36. The uppermost groove 240 is connected bya conduit 26| with chamber 1 I; the

middle groove 290 is connected by a conduit 202 with conduit 69; and thelowermost groove 209 is connected by conduits 203 and 204 with conduit26. Above the uppermost and below the lowermost groove 290, and betweeneach of said grooves, sleeve |99 is provided with an external groovehaving a packing ring to prevent leakage between said sleeve and bore|36.

Servo valve |49 is of the triple-spool type, consisting of threecylindrical valve portions accurately fitting the interior of sleeve|99, connected by two rod portions of reduced diameter. The upper end ofthe top valve portion has a conical shoulder 205 terminating in a smallupwardly projecting stem 296 which extends through a central aperture inwasher |48 and bearing |41 and serves as a centering means for thoseelements during the rotation of valve |49 about its vertical axis. Thereis a suflicient clearance between the outside of washer |48, bearing|41, plunger |38 and'bore |36 to permit a small flow of liquid fuel fromchamber 52 to chamber 83. This flow not only serves to lubricate andreduce the frictionof rotation between valve |49, washer |48 and bearing|41, but also equalizes the liquid pressures in chambers 52 and 83.

The middle valve portionvof servo valve |49 is provided with two ysmallV-shaped notches in its outer surface, in vertical alignment, as shownin Figures 3 and 4. These notches are of maximum depth and width atltheir bases and merge with the full diametral surface of valve |49 attheir points. When valve |49 is in its neutral position, as shown inFigures 3-and 4, the space between the middle and lowest valve portionsof valve |49 is in horizontal alignment with conduit 293; the spacebetween theA mi'ddlefand upper valve portions of valve |49 is inhorizontal alignment with the lower end of conduit 29|; while thecentral part of the middle valve portion of valve |49 between notchestherein is in hori- Zontal alignment with conduit 292'. When valve |49is in this neutral position, no owof liquid fuel can take place pastsaid valve. Since the width of the middle valve portion of valve |49between its notches is just equal to the width of the groove in sleeve|99 opposite conduit-V262, any movement of valve |49 up-or down lfromits neutral position will permit liquid fuel to flow past said valve,first through the notches and then through spaces between the middle andupper or lower valve portions of said Valve las its vertical movementcontinues. Thus, when valve |49 moves down from its neutral position,communication is established between conduits 29| and 292, while anupward movement of valve |49 from its neutral position establishescommunication between conduits 202 and 203. The vertical position ofvalve |49 depends upon the balance of vertical forces acting on saidvalve. These forces are: (l) the action of arms |5| of the speedgovernor which push valve |49 upwardly with an increase in engine speedand downwardly with a decrease of engine speed; 2) the expansion andcontraction of bellows |62 duc to engine acceleration and deceleration,as previously described, which in effect anticipates the action of arms|5| of the speed governor, and also moves valve |49 upwardly with engineacceleration; and (3) the compression in spring |46 which is Varied bythe throw of cam 88 on the manual control shaft.36. The compression inspring |46 is also adjusted byworm gear mechanism |40-'|45, as describedhereinabove.

Referring to Figures 3 and 4,.it will be noted that bore |31 has xedlypositioned in its lower end a sleeve 201 having a central passage 208which communicates at its lower end with conduit 1I and at its upper endwith a counterbore in which is seated a slidable sleeve check valve 209.Above valve 299. in bore |31 is a reciprocable and rotatable plunger 2|9which is counterbored at its lower end for the reception of a spring 2||that biases check valve 209 in a .closing direction. The upper end ofplunger 2|0 has a threaded socket for the reception of the threaded stem2| 2 of a cam follower 2|3 which bears against cam 81 and is restrainedfrom rotation by a pin 2|4 threaded through an extension on cam follower2|3 and fixed to casing 5|. Plunger 2|0 is provided with gear teeth 2|5engaged by a worm adjusting screw 2|6 for rotating said plunger, in allrespects similar to the worm adjusting screw for plunger |38 (see Figs.5 and 6). Rotation of plunger 2|! with reference to non-rotating stem 2I2 moves said plunger up or down in bore |31 and thus varies the tensionof spring 2|| and consequently the liquid pressure at which check valve200 opens and establishes communication between conduit 10 and conduit2|1 at any given position, of cam 81.

Referring to the right hand side vof Figure 3, it will be seen thatconduit 2|1 communicates with a chamber 2|8 which is also connected toconduit 10 through a ball check valve 2|9. Fixed to the top wall ofchamber 218 is a pressure responsive bellows 220 whose bottom wall ispivotally connected to a levery 222 whose other end bears against aspring 223 which biases check valve 2|9 ina closing direction. Theinterior of bellows 220 is connected by a conduit 224 t'o a thermal bulb225 which is located in the tail pipe I4 of the engine I so as to beexposed to the heat of the exhaust gases discharged through the tailpipe. Thermal bulb 225 is filled with a fluid which expands at apredetermined rate with temperature, so that as the temperature of theexhaust gases in tail pipe |4 rises, there is a corresponding increasein the fluid pressure in thermal bulb 225, and vice versa. This pressureis transmitted'through conduit 224 to bellows 220 which also expandscorrespondingly and thereby reduces the compression of spring 223, sothat whenever the maximum permissible temperature in*I tail pipe |4exists, the force of spring223 is reduced to a value which causes checkvalve 2|9 to be opened by the liquid pressure in conduit 10. The openingof valve 2|9 permits liquid fuel to lescape from conduit 10 throughchamber 2|8 and conduits 2|1 and 204 to discharge conduit 26. Thislowers the pressure CPS) in conduit 69 which in turn permits valve '58to open wider and thereby reduce the fuel flow through conduit 24 tofuel flow regulator 25 and hence to the engine. The reduction of fuelnow reduces the engine speed and hence temperature below the maximumpermissible temperature, whereupon valve 2|9 closes and steady stateoperation of the engine is resumed.

Connected in parallel with check valve 219 is a second check valve 226which is normally biased to closed position by a spring 221 whose upperend is seated in a cup 228 attached to the armature 229 of a solenoid230. A spring 23| normally maintainsA cup 228y in its lowermostposition, as shown in Fig. 3. when solenoid 2 30 is not energized. Wireleads 123| connect solenoid 230 to a source of electric energy and aswitch (not shown), so that whenever said switch is closed, solenoid ttis energized and armature 229 and cup 228 are raised to their uppermostposition. This reduces the compression in spring 221 so that check;valve 2% is opened and the pressure in conduits lll and tl is reduced toa value which reduces the fuel flow to the engine to one-half of thefior-f that would occur when valve 225 is closed. Solenoid operation ofvalve 22B thus permits the pilot cr engine operator to immediatelyreduce engine speed in case of emergency to prevent overspeeding oroverheating of the engine in case any of the automatic controls of fuelflow regulator 725 should fail.

Operation The principles of operation of my improved jet engine controlsystem are as follows:

(l) A constant displacement fuel pump 2| (as in Fig. i) or a variabledisplacement fuel pump 2| (as in Fig. 2) furnishes liquid fuel to theregulator 25 which acts to vary the rate of fuel delivery to the engineas required by the specifled operating conditions. 1n the arrangement ofFig. l, the difference between the fuel delivered by the pump and thequantity required by the engine is by-passed to the inlet side of thepump through a pressure-responsive relief valve d, while in thearrangement shown in Fig. 2, the quantity of fuel delivered to theengine is regulated by the regulator arm A3 of the pump 4|, in responseto the pressure differential between the unmetered fuel in conduit 24and the metered fuel in conduit 26.

(2) The fuel required by the engine to maintain its operating speed, orto meet the specified conditions of acceleration, is metered through ametering valve 95 which is specially contoured to give the necessaryrelation between fuel pressure and compressor rise or sensing pressure(p2-p1) (3) The pressure drop across the burner nozzles t anddow-divider 2l may be variable for a given rate of fuel flow. The flowthrough the metering valve Sii only is a function of the compressersensing pressure differential (p2-p1) and in case of stopping up of anozzle or other obstruction to fuel flow, the pressures adjustthemselves to maintain the fuel flow at a constant rate corresponding tothe speed of the engine and the position of the manual control lever 38.

(Il) During steady state (normal), or fixed manual lever position,operation of my control system, the tension of the speed governor spring|515 is substantially constant and is balanced against the thrust due tothe rotating governor weights |5i, Any slight increase or decrease ofengine speed causes the governor servo valve |49 to rise or fall, whichupsets the equilibrium of the relief valve 5ft, and consequently lowersor raises the pressure and therewith the quantity of fuel delivered, perunit of time, to the engine through the metering valve SG. rThisvariation in rate of fuel delivery to the engine will result incorrecting its speed in the desired direction,

(5) Any rate of change of engine -speed simultaneously creates acorresponding pressure in bellows it? which acts directly upon thegovernor servo valve H19 in the same direction as the weight arms of thespeed governor will act with the change of engine speed, thus resultingin an opposite change in fuel flow, due to movement of the servo valve|49. The effect of this additional pressure acting immediately upon theservo valve, before the weight arms of the speed governor have had timeto act, is to anticipate the action of the governor arms. rIhis not onlymakes the speed of the engine more quickly re-l sponsive to movements ofthe manual control lever, but also steadies the action of the controlsystem by eliminating hunting therein.

(6) The metered fuel pressure (pm), minus the compressor dischargepressure (p2) into which the fuel is discharged from burner nozzles 6,is a specified function of compressor sensing pressure (p2-p1) The fuelpump discharge pressure (pf) is determined from the equilibrium of therelief valve 54; the servo valve pressure (20s) is determined from theequilibrium of the check valve 25S (except when valve ZES or 226'opens);and. the metering head (pf-pm) is constant within the variation of theforces of these valve springs t and 2| with their displacements.

(7) With the manual control lever 38 in the full open position and theengine rotating at speeds below full R. P. M., the speed governor willbe in the cut-out position, i. e., the servo valve |49 will be displaceda little below the neutral position shown in Figures 3 and 4, so that arestricted flow of fuel occurs through the notches on the middel portionof servo valve M9 from the pump discharge to the rear side of the reliefvalve piston 62. This is equivalent to connecting the pump 2| dischargedirect to the rear side of the relief valve piston 62 through arestricting bleed hole. If the pump discharge is greater than thequantity of fuel that can be pushed through the metering valve orifices|94 by the metering head (10i-pm), then the relief valve 58 will be opento by-pass the excess fuel to the pump inlet 23, otherwise the pumpdischarge pressure (pf) would build up and disturb the equilibrium ofthe relief valve assembly 54.

(3) The metering valve 95 is a balanced valve actuated by the compressorsensing pressure (p2-101) and area of the metering orifices lt is also afunction of the compressor sensing pressure alone, so that to each valueof the sensing pressure there corresponds only one value of the orificearea, independent of the fuel pressures.

(9) The quantity of fuel metered by the-regulator 25 is given by theequation:

where F=fuel flow in pounds per second Cm=discharge coefficient throughmetering orifices |04 Am=area of metering orifices Iii-'1 pf=fueldensity g=acceleration of gravity pf=fue1 pressure on discharge side ofpump 2| in pounds per square inch pmzmetered fuel pressure in pounds persquare inch.

This quantity of fuel is sprayed into the combustion chamber 5 throughthe burner nozzles t. Since the pressure in the combustion chamber isequal to the compressor discharge pressure (p2), the pressure head whichforces the fuel through the restrictions due to the flow-divider 27 andthe burner nozzles 6 is (pm-pz), and if the fuel flow into thecombustion chamber is some function (f) of this pressure, as determinedby the design of the flow-divider, then:

F=f(pm-p2) (2) Equating Equations 1 and 2, we get:

144 CmAmpf 24J-pf- (rf-pm) fuerza) Equation 3 states that the fuelpressure head (pm-p2) is a function of the area (Am) of the meteringvalve orifices |04. Since Am is a function of the compressor sensingpressure (p1-p2), the fuel pressure head (pw-pz) is afunction of thecompressor sensing pressure, controllable for any particular applicationby the contour of the metering orifices |04.

Since the fuel pressure head (pm-p2) is dependent on the dischargecoefficients and the areas of the nozzle jets, etc., an advantage of mycontrol is that in case of clogging of one or more nozzles 6, which willchange the discharge characteristics of the nozzles, the fuel pressurewill adjust itself to maintain the fuel flow constant as given byEquation 1 above. In so d-oing, the absolute values of (pf) and (pm)will change, but their difference (pf-pm) will remain constant.

(l) When the speed governor is in cut-out position and the compressorsensing pressure is held constant, the metering head (pf-Dm) is aspecified function of the manual control shaft 35 rotation, the shape ofthe curve describing the specified function being determined by thecontour of the cam 88.

(11) The engine speed at which the speed governor cuts in and out (i.e., when servo valve |49 is open or closed) is a specified function ofthe rotation of manual control shaft 36. The speed setting of thegovernor in terms of manual shaft 36 rotation is determined by thecontour of the cam 88 (see Fig. 5). The servo valve |49 is in neutralposition at one and only one position of the governor weights |5|, andconsequently for each position of the manual cam 88 there is a singlevalue of the governor spring |46 tension. Any increase in engine speedwill raise the servo valve |49, establishing communication betweenconduits 202 and 203, and thus place a restricted by-pass opening inparallel with check valve 209. This permits the liquid fuel behindrelief valve piston 62 to escape into the main fuel passageway 26downstream from the main metering valve 96, thus reducing the servoValve pressure (ps) until it finally becomes equal to the metered fuelpressure (pm).

(12) The raising of the servo valve |49 and the consequent introductionof a by-pass across the check vvalve 209 therefore results in a loss ofmetering head, so that the fuel flow past the main metering valve 96 isno longer sufficient to maintain the required engine power output, andthe speed will fall, bringing the governor back to its neutral position.

If this were all that is involved, the speed governor would always bringthe engine speed back to the value corresponding to the manual controllever 38 setting. However, the governor servo valve |49 having beenreturned to neutral, there is nothing to restore the metering head toits required value, and the engine speed will continue to fall until theregulator 25 is in the condition indicated in subparagraph (7) above,and the metering head will then build up to normal. The

result of the governor action to correct Overspeed is therefore anover-correction, resulting in a drop of speed to below the desired valuebefore the desired speed is re-attained. For this reason, the fall inengine speed will not stop when it first reaches the new desired speed,but C011- tinues to fall to some lower speed, whereupon the oppositeforces acting through the governor and servo valve |49 cause the enginespeed to rise past the desired speed to some higher speed. The reversingaction of the speed governor then reduces the speed again past thedesired speed to some lower speed, and this oscillation in speedcontinues with progressively reduced amplitude through a series ofspeeds, alternately higher and lower than the desired speed, until thedesired speed is ultimately attained. This action of the governor, knownas huntingf is the same for either deceleration or acceleration of theengine- In order to eliminate this hunting" action of the speedgovernor, I have provided a means for anticipating the action of thespeed governor by applying an hydraulic pressure directly upon the servovalve |49 from a movement of the bellows |02 in response to any changein engine speed, as has been described hereinabove. The result of theaction of this anticipating mechanism is to change the engine speed morequickly and yet more gradually from one value to another, withoutovershooting the new desired value. This elimination of hunting not onlygreatly steadies the operation of the engine during acceleration anddeceleration, but makes the engine much more quickly and accuratelyresponsive to movements of the manual control lever.

Adverting now to a consideration of the mechanism hereinabove describedand illustrated in the drawings, the operation of my improved jet enginecontrol system is as follows:

When the engine is operating under steady state normal, or fixed manualcontrol lever position, the servo valve |49 is in neutral position, asshown in Figures 3 and 4, and the fuel pump 2| supplies liquid fuel tothe engine I through conduit 24, chamber I, manual cut-off valve 'I3-14.chamber 93, passage 94, space 98, apertures |03, Valve 96, meteringorifices |04, conduit 26, flowdivider 21, conduits 28 and 29, and burnernozzles 6 in combustion chamber 5. During steady state operation of theengine, the fuel pressure (pf) in conduit 24, and in passages up to mainmetering valve 96, is substantially constant and is determined by thedegree of opening of by-pass relief valve 58, which in turn depends uponthe loading of spring 68 and the hydraulic pressure (ps) in chamber 61.The rate of supply or flow of fuel to the engine is determined by thecombination of two variable factors: the area (Am) of the meteringorifices |04, and the metering pressure or head (pf-pm), (pm) being themetered fuel pressure in the conduit 26. The area (Am) depends upon theposition of the metering valve 96 which is determined by the differencebetween the compressor inlet pressure (p1) in bellows |29 and thecompressor discharge pressure (p2) in the bellows ||3, minus the loadingon spring Since the difference in pressures (p2-p1) is the rise acrossthe air compressor and is a measure of the mass air flow through theengine, the loading on spring determines the position of metering valve96 and the value of Am, at any given value of (p2-p1). Hence, theadjustment of the tensions in springs ||3 and ||9, by lock nuts ||8 andadjusting screw |20, respectively,

17 determines the mixture ratio of the fuel and air supplies of theengine.

Fuel isv supplied under pump inlet pressure (pi) from conduit 23 tochamber |23, through conduits 3| and |25, and also through conduit |26,chamber 52 and passage |24. From chamber |23, fuel under pressure (pi)also flows through passage |27 to chamber 30 and thence through passage62 to chamber 83. During steady state operation, the pressure (pi) inall these communicating chambers is the same, but may vary momentarilyduring acceleration or deceleration, or other variable conditions ofoperation, as hereinafter explained.

As indicated above, the pump discharge DleS- sure (pf) depends upon theservo pressure (ps) in chamber 61 of relief valve unit 5d, and so loneras servo valve |49 is exactly in its neutral position, as shown inFigures 3 and 4, its middle valve portion completely cuts oficommunication between conduits 20|, 202 and 293 and the pressure (ps) inconduit 68 and chamber 6l is constant. If now the operator advancesmanual control lever 38 to a higher speed index 35| on quadrant 19,shaft 36, which is connected to shaft 3l, rotates cam 88 in a clockwisedirection which pushes plunger |33 down and increases the compressionand force of spring |46 on servo valve |49, This increase in force ofspring |46 pushes servo valve |49 down, in opposition to the action ofarms and bellows |62, and establishes communication between conduits 20|and 2,02 and permits fuel under pressure (pf) to flow from chamber 'llthrough conduits 20|, 202 and 65| to chamber 61 in relief valve unit 54.The resulting increase in pressure (ps) in chamber el moves valve 58towards its seat 51, reducing the flow 0f by-passed fuel through conduit53, chambers 55 and 56 and conduit 3 l', and thereby increasing thepressure (pi) and flow of fuel through conduit 24, metering valve 96,orifices |04, conduit 26, flowdivider 2l and conduits 2t and 29 toburner nozzles 6.

With increased fuel now, the engine speed increases, with proportionateincrease in mass air iiow and compressor rise (pz-p1), (compressorsensing pressure). This increase in compressor rise (p2-p1) actingthrough bellows i3 and |29, lowers valve 96 in opposition to spring lil,and increases the area (Am) of orifices |04 to correspond with theincreased fuel flow from conduit 24 to valve 96. At the same time, owingto the closing of relief valve 58, there is a simultaneous drop in inletpressure (pi) in conduit 3| which is transmitted through conduit |25 tochamber |23. This drop in pressure (pi) in conduit 3| is alsotransmitted through passage lte, chamber 52 and passage |24 to chamber|23, and thence through passages |21 and 82 to chamber 83.

As they engine speed increases with increased fuel flow as describedabove, the weight arms |5| of the speed governor move outwardly bycentrifugal force, in proportion to the increase in engine speed, andaided by the expansion of bellows |62, raise servo valve |49 inopposition to the force of spring |46 until these forces balance,whereupon servo valve again returns to its neutral position and a stateof steady engine operation at the new higher speed ensues.

When shaft 36 is rotated by moving manual control lever 38 to the rightto a higher speed setting, cam 81 isrotated in a clockwise directionwhich pushes plunger 2|0 down and increases the compression and force ofspring 2| on checl-rV 18 valve 209. This increase in the force of spring2|| on valve 209 enables the valve to hold the higher pressure (ps) inconduits 'i0 and 69 which has been created by the downward movement ofservo valve |49 as just described above. When the increasing pressure(ps) in conduits 69 and l0 reaches a value exceeding the increased forceof spring 2||, valve 209 opens and permits fuel to flow from conduits'l0 and 69 through conduits 2H and 204 into conduit 26, until thepressure (ps) in conduits 69 and 10 falls to a value `below the force ofspring 2|| when valve 209 closes. Since the pressure in conduits 2|1 and264 is that of the metered fuel (pm), it is clear that valve 209 Willmaintain a pressure differential of (1Ds-pm), between conduits 69-10 andconduits 2|1-204, equal to the loading of spring 2| I, as determined bythe position of cam Sii and plunger 2|0, as long as servo valve |49prevents communication between conduits 202 and Zus. Thus, valve 209, bymaintaining a definite relation between the servo pressure (ps) and themetered fuel pressure (pm), serves to keep the pump discharge pressure(pr) in definite relationship with the metered fuel (pressurev (pm),since the pump discharge pressure (pf) is a definite function of theservo pressure (ps) through the action of relief valve 54.

With the engine in a state of steady operation, when manual controllever is moved to the left to a lower speed position, cam 88 will berotated in a counterclockwise direction which reduces the throw of thecam and permits plunger |38 to be raised by spring |46. This decreasesthe con pression and force of spring |46 on servo valve |49 whichpermits arms |5| of the speed governor to push servo valve |49 up,establishing communication between 202 and 203. Liquid fuel at apressure (ps) now flows from chamber 6i' through conduits 69, 202, 203and 224 to conduit 26,wherein the pressure is (pm). This iiow reducesthe pressure (ps) in chamber 6'! which permits relief valve 58 to openwider and by-pass more fuel around pump 2|, with resulting reduction inthe pump discharge pressure (pf) and fuel flow to metering valve 95.Accompanying the reduction in pump discharge pressure (pf) and fuel flowto valve 96, are actions through the regulator 25 in the oppositedirection from those described above for an increase in pump dischargepressure (pf) and fuel flow to valve 26, all of which result in areduced fuel supply to the burner nozzles 6 and a correspondingreduction in speed of the engine until the control system again becomesbalanced and steady operation of the engine at the desired reduced speedensues.

With the manual control lever 33 in any fixed position, thecorresponding speed of the engine will always tend to remain constant.But, if for any reason there should occur an undesired in crease inengine speed, the accompanying increase in compressor rise (pie-p1)acting through bellows ||3 and |29 will at once depress valve 26 whichwill increase the fuel ow and speed of the engine. This increased speed,acting first through bellows |62 and then through arms |5| of the speedgovernor, will immediately raise servo valvel |49, which will reduce thepressure (ps) in chamber 6T, open relief valve 50, reduce the pumpdischarge pressure (pf) in conduit 24, and reduce the fuel fiow to theengine until. its speed falls 01T to that corresponding to the settingof control lever 38. As long as the actual enginespeed exceeds thedesired engine speed corresponding to the position of manual controllever 33, the upward thrust of bellows |62 and weight arms ISI of thespeed governor will iaintain servo valve |49 in raised position untilthe falling speed of the engine again reaches the desired speed,corresponding to the position of manual control lever |38, whereuponservo valve M9 will return to its neutral position and the engine willthereupon continue to rotate at the desired speed in a state of steadyoperation. Conversely, if an undesired decrease in engine speed shouldoccur, the reverse action of the above mentioned elements willautomatically bring the engine up to the desired speed corresponding tothe position of manual control lever 38.

Valve 2|9 of the thermal override control remains seated at all timesunless the temperature in the tail pipe I4 exceeds the prescribedmaximum safe limit and the thermal override control has no effect uponthe regulator 25. Whenever the temperature in the tail pipe exceeds theprescribed maximum safe limit, bellows 220 raises the right end of lever222 and reduces the force of spring 223 upon ball check valve 2I9,whereupon valve ZIB opens and permits liquid fuel to flow from conduit Iinto conduit 2I'I, regardless of the action of valve 209. This flowreduces the pressure (ps) in chamber 61 and permits relief valve 58 toopen wider and reduce the pump discharge pressure (pf) and the flow offuel to metering valve 96, which in turn reduces the flow of fuel to theengine and the speed of the engine. The reduction in engine speedreduces the temperature in the tail pipe I4 until it reaches the maximumsafe limit, whereupon bellows 220 moves the right end of lever 2,22 downand valve EIS closes. Thus, the temperature of the engine can neverexceed a prescribed safe limit regardl and hermetically sealing it,instead of connecting it to air inlet 2. The difference in pressure (Pz)in bellows I3 and (Po) in bellows |29 would then represent the absolutepressure rise across compressor 3, which is also a measure of the massair flow through the engine, so that the same results would be obtainedin the operation of fuel flow regulator 25 by suitable changes incalibration of its elements. Y

While I have shown and described the preferred embodiment of myinvention, I do not limit it to the constructional details disclosed byway of illustration, as these may be changed and modified by thoseskilled in the art, without departing from the spirit of my inventionnor exceeding the scope of the appended claims.

I claim:

l. A fuel and speed control apparatus for an internal combustion enginecomprising: an engine driven, constant displacement fuel pump forsupplying fuel to said engine, a by-pass relief valve for varying thedeliveryof said pump, and means, responsive to engine speed and rate ofair now through the engine, acting on said valve for automaticallyregulating the flow of fuel from said pump to said engine in accordancewith predetermined operating requirements of the en gine; said meansincluding a centrifugal speed governor and means actuated by rotatinginertia element for anticipating the action of said governor.

2. A fuel and speed control apparatus for an internal combustion enginehaving an air compressor, comprising: an engine driven, constantdisplacement fuel pump for supplying fuel to said engine, a by-passrelief valve for varying the delivery of said pump, and means,responsive to the pressure rise across the compressor and acting incooperation with said valve, for automatically regulating the flow offuel from said pump to said engine in accordance with predeterminedoperating requirements of the engine; said means including a centrifugalspeed governor and means actuated by a rotating inertia element foranticipating the action of said governor.

3. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever, comprising: an engine driven, constantdisplacement fuel pump for supplying fuel to the engine, a by-passrelief valve for varying ing the delivery of said pump, and means,responsive to said control lever and acting on said Valve, forautomatically regulating the flow of fuel from said pump to said engine,so as to produce a constant engine speed corresponding to the positionof said control lever under varying engine operating conditions; saidmeans including a centrifugal speed governor and means actuated by arotating inertia element for anticipating the action of said governor.

4. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever, comprising: an engine driven, constantdisplacement fuel pump for supplying fuel to the engine, a ley-passrelief Valve for varying the delivery of said pump, and means,responsive to said control lever and acting on said valve, forautomatically regulating the flow of fuel from said pump to said engineso as to vary the engine speed in proportion to the movement of saidcontrol lever; said means including a centrifugal speed governor andmeans actuated by a rotating inertia element for anticipating the actionof said governor.

5. A fuel control apparatus according to claim 1, which includes meansfor modifying the action of said governor to prevent the speed and/ortemperature of the engine from exceeding selected, maximum safe limits.

6. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever, comprising: an engine driven, constantdisplacement fuel pump for supplying fuel to the engine, a by-passrelief valve for varying ing the delivery of said pump, and means,responsive to said manual control lever and acting on said valve, forautomatically regulating the flow of fuel from said pump to said engineso as to maintain a constant engine speed corresponding to the positionof said manual control lever despite variations in pressure, load andtemperature conditions of the engine; said means including a centrifugalspeed governor and means actuated by a rotating inertia element foranticipating the action of said governor.

7. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever comprising: an engine driven, constantdisplacement fuel pump for supplying fuel to the engine, a by-passrelief valve for varying the delivery of said pump, and means,responsive to said manual control lever and to pressure, speed andtemperature conditions of the engine and acting on said valve, forautomatically regulating the flow of fuel from said pump to said enginein accordance with predetermined operating requirements of the engine;said means including a centrifugal speed governor and means actuated hy-a rotating inertia element for anticipating the action of saidgovernor.

8. A fuel and speed control apparatus for an internal combustion enginecomprising: an engine driven constant displacement fuel pump forsupplying fuel to the engine, a ley-pass relief valve for varying thedelivery of said pump, and means, comprising a plurality of component,coordinated hydraulic systems responsive to pressure, speed andtemperature conditions of the engine and acting on said valve, forautomatically regulating the flow of fuel from said pump to said enginein accordance with predetermined operating requirements of the engine;said means including a centrifugal speed governor and means actuated hya rotating inertia element for anticipating the action of said governor.

9. A fuel control apparatus according to claim 2, wherein the fuel flowregulating means includes a plurality of component, coordinatedhydraulic systems each responsive respectively to pressure, speed andtemperature conditions of the engine and all coacting to modify theaction of said governor. I

10. A fuel control apparatus according to claim 3, wherein the fuel flowregulating means includes `a plurality of component, coordinatedhydraulic systems each responsive respectively to pressure, speed andtemperature conditionsof the engine and all coacting to modify theaction of said governor.

ll. A fuel `control apparatus laccording to claim 4, wherein the fuelfiow regulating means includes a plurality of component, coordinatedhydraulic systems each responsive respectively to pressure, speed andtemperature conditions'of the engine and all coacting to modify theaction of said governor.

12. A fuel control apparatus according to claim 6, wherein the fuel flowregulating means includes a plurality of component, coordinatedhydraulic systems each responsive respectively to pressure, speed andtemperature conditionslof the engine and all coacting to modify theaction of said governor. I

13. A fuel control apparatus according to claim '7, wherein the fuelflow regulating means includes a plurality of component, coordinatedhydraulic systems each responsive respectively to pressure, speed andtemperature conditionsof the engine and all coacting to modify theaction of said governor.

14. A fuel control system according to claim 7, wherein the-fuel flowregulating means includes a plurality of component, coordinatedhydraulic systems, each respectively responsive to pressure, sneed andtemperature conditions of the engine and all coacting to modify theaction of said governor.

15. A fuel and speed control apparatus for an internal combustion enginehaving an air compressor, comprising: a pump for supplying fuel to theengine, a fuel metering valve means, responsive to the pressure riseacross the compressor, for regulating the flow of fuel from said pump tosaid engine in `accordance with the flow of air through said compressor;centrifugal speed governor means, responsive to engine speed for ertiaelement for anticipating the action of said governor means.

16. A fuel and speed control apparatus according to'claim l5, whichincludes means coacting to modify the action of said governor and thusautomatically vary the pressure of the fuel on the upstream side of saidmetering valve in accordance with the speed of the engine.

17. A fuel and lspeed control apparatus according to claim 15, whichincludes means coacting to modify the action of said governor and thusvary the pressure of the fuel on the upstream side of said meteringvalve in accordance with the temperature of the engine exhaust gases sothat the temperature of the engine never exceeds a predetermined safelimit.

18. For an internal combustion engine having a manual control lever, afuel and speed control apparatus according to claim 15, which includesmeans responsive to said manual control lever and coacting with saidgovernor to modify its action and thus vary the pressure of the fuel onthe upstream side Yof the metering valve so that the speed of the engineis responsive to the movement of said manual control lever.

19. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever and an air compressor, comprising: a pumpfor supplying fuel to the engine, a metering valve, responsive to thepressure rise across the compressor, for regulating the flow of fuelfrom said pump to said engine in accordance with the ow of air throughsaid compressor, and means for varying the pressure of the fuel 0n theupstream side of said metering valve in accordance with the speed of theengine and/or the movement of said manual lever; said means including acentrifugal speed governor and means actuated by a rotating inertiaelement for anticipating the action of said governor.

20. A fuel and speed control apparatus according to claim 19, whichincludes means c0- acting to modify the action of said governor and thusvary the pressure of the fuel on the upsteam side of the metering valvein accordance with the temperature of the engine exhaust gases so thatthe temperature of the engine never exceeds a predetermined safe limit.

21. A fuel and speed control apparatus for` an internal combustionengine having a manual control lever and an air compressor, comprising:a pump for supplying fuel to the engine, a metering valve, means forvarying the opening of said valve in proportion to thepressure riseacross the compressor, and means for varying the pressure of the fuel onthe upstream side of said valve in accordance with the speed of theengine and/or the movement of said manual control; said last meansincluding a centrifugal speed governor and means actuated by a rotatinginertia element for anticipating the action of said governor.

22. A fuel and speed control apparatus `according to claim 21, whichincludes means for varying the pressure of the fuel on the upstream sideof the metering valve in accordance with the temperature of the engineexhaust gases so that the temperature of the engine never exceeds apredetermined safe limit.

23. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever, comprising: a pump for supplying fuel tothe engine, and means for automatically regulating the pressure and iloWof fuel from said pump to said engine in accordance with pressure, speedand temperature conditions in the engine,

and in proportion to the movement of said manual lever, therebyproducing a constant engine speed corresponding to the position of saidmanual control under varied operating conditions of said engine; saidmeans including a centrifugal, all speed governor Vand means actuated bya rotating inertia element for anticipating the action of said governor.

24. A fuel and speed control apparatus according to claim 23, whereinmeans actuated by a rotating inertia element is driven by the engine andcomprises means coacting with said governor, for selectively changingthe speed of the engine without hunting of said regulating means for thenew selected speed.

25. A fuel and `speed control apparatus according to claim 24, whereinthe fuel flow regulating means Ycomprises a plurality of component,coordinatedA hydraulic systems each responsive respectively to pressure,speed and temperature conditions of the engine and all coacting tomodify the action of said governor.

26. A fuel and speed control apparatus for an internal combustion enginehaving a manual control lever, comprising a pump for supplying fueltothe engine, means for automatically regulating the pressure and flowof fuel from said pump to said engine so as to produce a constant enginespeed `corresponding to the position of said control lever under variedopera-ting conditions, and

'means, comprising a centrifugal, all speed governor and means actuatedby a rotating inertia element driven by the engine for anticipating theaction of said governor, for preventing hunting of said fuel regulatingmeans when the engine Yspeed. is changed by movement of said controllever.

27. A fuel and speed control apparatus for an internal combustion enginehaving an air compressor and a manual control lever, comprising: a pumpfor supplying fuel to the engine, means, including an engine driven,centrifugal, all speed governor, for automatically regulating thepressure and flow of fuel from said pump to said engine so as to'produce a constant engine speed corresponding to the position of saidcontrol lever under varied operating conditions, and means,

responsive to a rotating inertia element driven by the engine foranticipating the action of said governor, whereby change of engine speedis more quickly responsive to movement of said control lever and huntingof said regulating means is prevented.

28. In a fuel and speed control apparatus for an internal combustionengine, a centrifugal, all speed governor driven by the engine andcomprising: means for varying the W of fuel to the engine in accordancewith engine speed and means for anticipating the action of said governorcomprising a fluid pressure regulating valve rotated in constant speedrelation to said governor and a rotating inertia element elasticallyvconnected to and driven vby said valve and adapted to vary the openingof said valve in either direction in proportion to the rate of change inthe speed of rotation of said valve.

29. A fuel `and speed control apparatus as in claim 28, including apressure responsive element subject to a fluid pressure regulated bysaid valve and coacting with said governor to supplement the action ofsaid governor.

30. A fuel and speed control apparatus for an internal combustion enginecomprising: an engine driven variable displacementl fuel pump forsupplying fuel to said engine, means for varying the delivery of saidpump, and means acting on said delivery varying means for automaticallyregulating the, fuel flow from said pump to said engine in accordancewith predetermined operating requirements of the engine; said last meansincluding a centrifugal speed governor and means actuated by a rotatinginertia element for anticipating the action of said governor.

LEIGHTON LEE II.

References Cited in the ille of this patent UNITED STATES PATENTS NumberName Date 2,245,562 Becker June 17, 1941 2,306,953 Jung Dec. 29, 19422,407,982 Hanna et al Sept. 24, 1946 V2,411,065 Silvester Nov. 12, 19462,422,808 Stokes June 24, 1947 2,441,948 Atkinson May 25, 1948 2,457,595Orr Dec. 28, 1948 2,472,181 Werth June 7, 1949 2,509,648 Mock May 30,1950 2,514,674 Schorn July 11, 1950 2,581,275 Mock Jan. 1, 1952 FOREIGNPATENTS Number Country Date 595,152 Great Britain Nov. 27, 1947

